Aircraft and other large objects must occasionally be weighed. The weighing procedure typically utilizes a plurality of load cells upon which the entire weight of the object collectively rests. The load cells couple to transducers which provide electrical signals. These electrical signals may be measured, and the electrical measurements may be converted into a weight. The sum of weights resulting from outputs measured at each of the plurality of load cells equals the total weight of the object. In addition, the individual weights are useful in calculating center of gravity parameters.
A platform weighing system provides one conventional solution to the problems posed in weighing aircraft or other large objects. In using platform systems, the object is rolled onto a plurality of platforms. Typically, one platform resides under each of the object's wheels. Each platform contains at least one load cell which senses weight applied to the platform.
However, conventional platform weighing systems fail to accurately weigh such objects in the field environments within which such systems are often used. One problem concerns the application of side loads to the load cells which measure the object's weight. Such side loads may be caused by a less than precisely level surface upon which the platforms are being used, or they may be caused by various mechanical configurations of landing gear or other wheel support structures. Consequently, if side loads are not adequately tolerated, weight measuring accuracy diminishes. For example, although a strain gauge type of load cell is known to provide a highly accurate output when not subjected to side loads, the application of a side load so severely and detrimentally influences such a load cell's output signal that a highly accurate measurement is not attainable.
Moreover, such platform weighing systems tend to operate in electrically noisy environments and over a wide variation in temperature. The electrical circuits used to measure load cell output signals in conventional platform weighing systems are so influenced by noise, the environment, temperature, and the like, that they fail to achieve acceptable accuracies.
Thus, a need exits for an improved platform weighing system which produces highly accurate measurements in spite of side loads or external influences on electrical circuits.